JPH0422659A - Impact printer - Google Patents

Abstract

PURPOSE:To improve a silencing effect by providing a paper separator having a plurality of cavities of different volumes for performing a resonance type silencing near the exit of a printing sheet. CONSTITUTION:A continuous recording sheet 3a having pin holes is passed at an interval between an upper case 22a and the lower surface 19b of a paper separator 19, conveyed by a tractor feeder 16, passed through an interval between a paper pan 15 and a paper guide 17, wound on a platen 2 and conveyed to a sheet feed roller 14 to become a printable state. A printing head l in which an electric signal is applied is moved axially of the platen 2 by a carriage motor 8 to print while driving a printing wire by a solenoid formed in the head. Since noise is almost sealed by an upper case 22, a lower case 13, a clear cover 23, a soundproofing cover 24, the separator 19, etc., it is fed out of a supply/discharge port of the sheet 3, but resonance-absorbed by a resonance silencer composed of the separator 19, the cover 24 and the case 22a.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an impact printer that selectively drives wires arranged at high density to print on recording paper via an ink ribbon.

BACKGROUND OF THE INVENTION FIG. 7 shows an exterior case of a conventional impact printer, which will be described below.

An impact printer basically consists of a print head 1, a platen 2, an ink ribbon cassette 4, and a paper separator 1.
9. It is formed from a lower case 13, an upper case 22, and a clear cover 23. The continuous recording paper 3a with pin holes passes between the upper case 22a and the paper separator 19, is conveyed by the tractor feeder 16, passes through the gap between the vapor pan 15 and the vapor guide 17, is wound around the platen 2, and is moved to the paper feed roller. 14, the print head 1 is conveyed and becomes ready for printing, and to which a print signal is applied from an electric circuit (not shown), the print head 1 moves in the axial direction of the platen 2 by the driving force of a motor or the like, and then prints. When printing of one line is completed, the recording paper 3 is fed by one line by a paper feed motor (not shown), and printing is performed.

By repeating this operation, characters, figures, etc. are printed on the recording paper 3.

Problems to be Solved by the Invention The above conventional example has the following drawbacks. Impact dot printers require an entrance/exit (opening) for the recording paper, and because the opening is wide, the sound from the impact head, etc. inside the outer case of the impact printer escapes to the outside, creating a noise problem. Ta.

As a solution to this problem, there was a method that installed a resonant type sound-muffling member near the entrance/exit of the printing paper, but this member has a cavity of a certain volume, and the volume is determined by the volume of this cavity. Even if a silencing effect can be obtained for sounds at a resonant frequency, no silencing effect has been achieved for sounds other than that frequency.

Means for Solving the Problems In order to solve this problem, the present invention provides a paper separator having a plurality of cavities each having a volume for resonance-type noise reduction near the entrance/exit for printing paper.

Effect: This configuration results in the loss of sound energy at a frequency that is dependent on each volume of the cavity. The cavities have various volumes to provide broad band sound deadening.

Embodiment An impact printer according to an embodiment of the present invention will be described below.

1 and 2 show a side perspective view and a top perspective view of an impact dot printer according to an embodiment of the present invention, and FIG. 3 shows a perspective view of a paper separator.

In FIG. 1, reference numeral 1 denotes a print head that includes a plurality of solenoids for driving print wires (pins). 2
is a cylindrical platen that receives the impact of the print head I, and also conveys the recording paper 3. Here, the platen 2 may have a cylindrical shape, or may have a flat bar shape if the recording paper 3 is conveyed by another means. 4 is an ink ribbon cassette containing an ink ribbon. The print head 1 and the ink ribbon cassette 4 are mounted on a carriage 5, and are moved parallel to the platen 2 using a carriage shaft 6 and a carriage guide 7, which are arranged parallel to the platen 2, as guides. 8 is a carriage motor, and a carriage motor pulley 9 serves as a means for transmitting the rotational motion of the carriage motor 8.
a. It is used as a driving force to move the carriage 5 (print head 1) via the timing heald 9b. It is also possible to use a wire or the like instead of the timing belt 9. 1O (two-dot chain line) is the chassis side plate,
The platen 2, carriage shaft 6, and carriage guide 7 are supported in parallel. The chassis side plate 10 is fixed to a chassis base 11 (double-dashed line). Further, the carriage motor 8 is provided with a vibration-proof rubber 12a to insulate vibrations.
and is attached to Chassis Base II. The chassis base 11 is attached to the lower case 13 using the boss 1.
3a via a vibration isolating rubber 12b, so as not to transmit vibrations of the chassis base 11 to the lower case 13. Reference numeral 14 denotes a cylindrical paper pressing roller, whose entire width is in contact with the platen 2 so that no gap is formed. A vapor pan 15 serves as a guide when the recording paper 3 is inserted. A tractor feeder 16 has a pin belt and feeds the continuous recording paper 3a having a bin hole. A vapor guide 17 serves as a guide when inserting the cut recording paper 3b and the continuous recording paper 3a. A vapor deflector 18 serves as a guide when inserting the recording paper 3b and when discharging the recording paper 3. 19 is a paper separator,
Resonant silencing chamber 20 with multiple heights, ie, various volumes
a, 20b (cavity) on the upper surface 19a and lower surface 19b of the paper separator 19, and in the feeding and discharging direction of the recording paper 3 (
direction) and the main axis direction of the platen 2 (direction B). Here, a perspective view of the paper separator 19 is shown in FIG. Also, the paper separator 19 is connected to the chassis side plate lO.
It is rotatable via a fulcrum 21a of an attachment 2I (double-dashed line) fixed to. The fulcrum 21a may also be constructed from a shear side plate. 22 is an upper case, which is fitted with the lower case 13. The upper case 22a, which also serves as a guide for the continuous recording paper 3a, serves as a stopper for the paper separator 19. Note that the continuous recording paper 3a is inserted into the bottom surface f of the paper separator 19.
9b and the continuous recording paper 3a can pass through, and the resonant muffling chamber 20b located on the lower surface +9b of the paper separator 19 and the upper case 22a constitute a resonant muffler. A clear cover 23 is made of a transparent or semi-transparent material, and allows the recording state by the print head 1 and the running state of the recording paper 3 to be observed. 24 is a soundproof cover, which is rotatable via a fulcrum 23a at one end of the clear cover 23. Also, the part where the recording paper 3 passes is the upper surface of the paper separator I9 +
9a and a resonant silencing chamber 2 on the upper surface 1.9a of the paper separator 19, which is narrow enough to allow the recording paper 3 to pass through.
0a and the soundproof cover 24 constitute a resonance type muffler. The operation will be explained below.

The continuous recording paper 3a having a bottle hole passes through the gap between the upper case 22a and the lower surface 19b of the paper separator 19, is conveyed by the tractor feeder 16, passes through the gap between the vapor pan I5 and the vapor guide 17, and is wound around the platen 2. The paper is transported by the paper feed roller I4 and becomes ready for printing.The print head 1 receives an electric signal from an electric circuit (not shown) and is moved in the axial direction of the platen 2 by the carriage motor 8, and the print head 1 is moved into the print head by the carriage motor 8. Printing is performed by driving the printing wire using the solenoid. When printing of one line is completed, the recording paper 3 is fed by one line by a paper feed motor (not shown), and printing is performed again in the above-described manner. By repeating this operation, characters, figures, etc. are printed on the recording paper.

The noise generated by the above-mentioned printing operation and the movement of the print head in the axial direction (direction B in Figure 2) of the platen 2 is as follows.
Since the upper case 22, the lower case 13, the clear cover 23, the soundproof cover 24, the paper separator 19, etc. are in a completely airtight state, the recording paper 3 will come out from the inlet/outlet, but the paper separator 19, a soundproof cover 24, and an upper case 22a.

Figures 5 and 6 show the silencing principle and effects of the resonator (transmission loss and
TL). In the figure, a sound wave from a sound source 25 resonates with an air column vibration system in a resonant silencing chamber 27 via an introduction chamber 26. Assuming that the wave is a sound wave or a plane wave, the cross-sectional area of the introduction chamber 26 is SO1, and the cross-sectional area and height of the resonance silencing chamber 27 are Sl and Lb, respectively.

When the frequency of a sound wave is f and the speed of sound is C, the transmission loss T L (d
B) is given by the following equation.

TL= 101ag(1+ -jan"(k ・l, b
) ) - (+) where M = S1/SO, k = 2πf/C
It is. Further, the resonance frequency fp is given by the following equation.

Note that the transmission loss T L (dB) changes with a peak at the resonance silencing frequency fp, as shown in FIG. Therefore, resonant silencers can be very effective at certain frequencies. The present invention aims to reduce the noise level by intentionally generating this resonance phenomenon inside the muffler.

Here, as can be seen from equation (2), the resonant frequency fp is a function of the height Lb of the resonant muffling chamber, and as can be seen from Fig. 6, the transmission loss (muffling effect) TL of the resonant muffler is The height of the resonant silencing chambers 20a, 20b of the paper separator 19 (direction C in FIG. 1) is changed because the height of the resonant silencing chambers 20a, 20b of the paper separator 19 is changed (direction C in FIG. 1).
By arranging b, it is possible to increase the number of resonance frequencies fpO and reduce the noise level for a large number of frequencies.

In addition, a resonant muffler is constructed in which the resonant frequency fp matches the high frequency of the noise level against noise generated by the printing operation and the movement of the print head in the axial direction (direction B in FIG. 2) of the platen 2. By doing so, more effective noise reduction can be achieved.

Further, this mechanism is applicable not only to impact dot printers but also to printing devices using impact or the like.

Effects of the Invention As described above, the present invention provides a paper separator with a plurality of cavities that serve as resonant silencing chambers with different volumes to constitute a resonant muffler. We can provide you with a noisy impact printer.

[Brief explanation of the drawing]

FIG. 1 is a horizontal perspective view of an impact printer according to an embodiment of the present invention, FIG. 2 is a top perspective view of an impact printer according to this embodiment, FIG. 3 is a perspective view of a paper separator according to this embodiment, and FIG. 5 is a horizontal perspective view of an impact printer according to another embodiment of the present invention, FIG. 5 is a diagram showing the principle of noise reduction, and FIG.
The figure is a graph explaining the present invention in detail, and FIG. 7 is a horizontal perspective view of a conventional impact printer. 1... Print head, 2... Platen,
3... Recording paper, 4... Cassette with ink ribbon, 5... Carriage, IO...
... Chassis side plate, 12 ... Anti-vibration rubber, 13.
... lower case, 19 ... paper separator, 20 ... resonance silencing chamber, 22 ... upper case, 23 ... clear cover, 24・・・・・・
...Name of soundproof cover agent: Patent attorney Shigetaka Awano and 1 other person
Toto (/-rz)

Claims (1)

[Claims] An impact printer in which a printing unit including a platen is covered with an exterior case having an entrance/exit for printing paper, and a paper separator having a plurality of cavities with different volumes on a surface facing the printing paper is provided near the entrance/exit for printing paper. An impact printer characterized by: